Amateur question but bear with me....

[russ9898]

Hi everyone,

Couple of questions. Simple but just seeking clarification more than anything.

Heat resistant flex - Is it the inner cores, outer sheath or both which are heat resistant?

Reason being ive stumbled across an urn which all the wiring to the heating elements/control gear has disintegrated mainly due to age. (Aluminuim/silver cores on the cable).

The elements are testing fine and the rest of the urn seems fundamentally sound. So i plan to rewire the stat connections, elements, main switch etc etc. Now im pretty sure you cant buy heat proof singles easily? So plan on using flex and stripping the inner cores out. I just wanted to check that they were heatproof first.

Secondly what is the current carrying capacity of 1.5/2.5 flex? Ive sold my big red book and my 17th edition amendment book hasn't turned up yet. Would like to rewire the urn tommorow so if someone would check for me it would be appreciated.

Thanks alot.

Russ

 

[M107]

Good question.

The inner insulation of the flex is usualy the same rubbery type as the outer sheath, so I would hazard a guess it in itself is heat resistant to a degree....but others may know for sure.

Butyl heat res flex

1.5 flex good to 16amp

2.5 flex good for 25amp

Edited to say ; no calcs used, just look at the TLC site.

 

[Manator]

The outer sheath is the first primary heat resistant shield, the inner cores are from the same material and offer the same protection from internal heat, but not in the same way as the outer. Remember heat resistant cable is used in high temperature environments, and is fitted subject to outside influence.

 

[SPECIAL LOCATION]

Where you terminate a flex onto an immersion heater element...

The outer sheath is stripped back..

But the stripped back inner cores are actually in probably the hottest place!

Guinness

 

[russ9898]

Good question.The inner insulation of the flex is usualy the same rubbery type as the outer sheath, so I would hazard a guess it in itself is heat resistant to a degree....but others may know for sure.

Butyl heat res flex

1.5 flex good to 16amp

2.5 flex good for 25amp

Edited to say ; no calcs used, just look at the TLC site.

I looked on the TLC website just after i posted and saw the butyl heat resistant flex and their corresponding ratings. I need some 4mm butyl to run from the 32a plug ive installed to the urn so glad ive spotted that. Lets hope Edmundsons have some in stock tomorrow.

Where you terminate a flex onto an immersion heater element...The outer sheath is stripped back..

But the stripped back inner cores are actually in probably the hottest place!

Guinness

Very good point sir. Didn't think about it like that. Seems like heatproof flex stripped down will do the job nicely then.

 

[Sidewinder]

"Tri rated wire" used mainly for machinery panels and internal wiring such as found on domestic appliances is 105 deg C rated.

It also meets the relevant BS, CSA & UL requirements, hence the tri bit.

 

[Andy™]

you can get singles with a braided heat resistant sheath - its used in ovens / hobs etc

not sure where you can get it, but it is available

 

[russ9898]

Cheers for the replies guys.

I ordered some Tri rated singles and 4.0mm butyl flex from the wholesalers this morning. Cant you tell its coming upto stock take...they hadnt even got insulated female spade crimps in stock.

 

[roys]

Ahhh is that what the tri means, I have wondered about that in the past, good one. Cheers

"Tri rated wire" used mainly for machinery panels and internal wiring such as found on domestic appliances is 105 deg C rated.It also meets the relevant BS, CSA & UL requirements, hence the tri bit.

 

[airmax76]

Hi the outer flex which is usually heat resistent

 

[Andy™]

Ahhh is that what the tri means, I have wondered about that in the past, good one. Cheers

except the larger sizes - they are Bi-rated

 

[Sidewinder]

Andy,

If they are Bi-Rated, then they ain't Tri-Rated are they! ]

---------- Post Auto-Merged at 19:20 ---------- Previous post was made at 19:16 ----------

Just checked and it is only "normally" above 120mm sq singles that are Bi-Rated.

This is Canoeboy territory, don't think I have ever installed singles this size!

---------- Post Auto-Merged at 19:22 ---------- Previous post was made at 19:20 ----------

Also useful?

http://www.triratedcable.co.uk/downloads/en_GB/Eland_Tri-Rated_Size_Colour_Guide.pdf

---------- Post Auto-Merged at 19:22 ---------- Previous post was made at 19:22 ----------

Along with this?

http://www.triratedcable.co.uk/downloads/en_GB/Tri-Rated_Cable_BS6231.pdf

 

[kerching]

I mistakenly asked my suppliers for some 400mm trirated singles. Told me [correctly] that it did not exist. I called them all the names under the Sun, and then realised that it was birated...and made myself look like a total prannock. But I did apologise profusely to them. Excellent stuff to work with..... :coat

 

[Phoenix]

[quote name='Andy

 

[tom1]

[quote name='Andy